Overload clutch



H. C. HOLLINGER ovERLoAD CLUTCH 2 SHEETS-SHEET 1 March 17, 1953 Filed Aug. '7, 1947 2 SHEETS-SHEET 2 @www OVERLOAD CLUTCH Il Il March 17 1953 Filed Aug. 7'

. in the form of a sleeve which Patented Mar. 17, 1953 UNITED STATES OVERLOAD CLUTCH Harry C. Hollinger,

Farquhar Company, Pennsylvania,

York, Pa., assigner to A. B.

York, Pa., a corporation of Application August 7, 1947, Serial No. 767,040

1 Claim.

This invention relates to overload clutches and is particularly related to those overload clutches wherein resiliently pressed plungers retain the power transmission until the overload point in power is reached.

The primary object of this invention is the provision of an improved power transmitting overload clutch.

Another object of the invention is the provision of an overload clutch wherein during the normal operation, there is no unbalanced thrust against the power shaft or against the driven shaft or rotary member to which the power is driven.

Still another object of the invention is the provision of an improved overload clutch having a supporting member for carrying the clutch and in which there is no unbalanced thrust in either the direction of the driving or the direction of the driven member.

A still further object of the invention is the provision of an improved overload clutch wherein there are a plurality of resiliently pressed depression contacting members having a means for varying the resilient pressing action simultaneously while maintaining an equal pressing action during and after adjustment.

Another and still further object of the invention is the provision of an improved overload clutch wherein the drive and driven members are free from unbalanced thrust and wherein a slight increase toward overload is taken up without the clutch release taking place.

Other and further objects of the invention will be apparent to those skilled in the art from a reading of the com-plete specification and claim.

Referring to the drawings wherein are illustrated two modifications of the invention.

Fig. 1 is a longitudinal sectional view of the invention as applied to an axial transmission.

Fig. 2 is a sectional detail view taken on the line 2-2 of Fig. 1.

Fig. 3 is a sectional detail view taken on the line 3-3 of Fig. 1.

4 is a longitudinal sectional view of a modified form of the invention showing a chain take-olf at right angles to the power shaft.

Fig. 5 is a detail fragmental view taken on the line 5-5 of Fig. 4.

Fig. 6 is a detail sectional view taken on the line E-S of Fig. 4.

Similar reference characters refer to the same or similar parts throughout the specification and drawing.

Referring particularly to Fig. 1, the numeral 2) designates the drive shaft from which the power is derived. This shaft 'it has a threaded portion 29a which may be integral or may be is suitably brazed or welded to the shaft 20. A limiting collar 20h is provided to hold the parts in position as will be later made clear. This collar 29h is preferably rigid with the shaft 2t and may be integral therewith or a part of the sleeve Zta.

Surrounding the drive or power shaft 2G is the main body 2l of the overload clutch. This body member 2l is provided with a keyway 2id. The shaft 2G has a keyway slot in which is a Woodruff key 22. This key extends into the slot 21a and prevents relative turning between the body member 2i and the shaft 2B.

The body member 2l is provided with borings 2th which in the embodiment illustrated, are three in number. These borings are arranged with their axes parallel to the axis of the shaft 253 and each carries a pair of o-ppositely disposed spring-pressed plungers or pistons 23. These plungers or pistons 23 are hollow and are provided with rounded ends 23d. Each pair of plungers or pistons 23 has a spring 2d, the ends of which are in the hollow portions of the pistons 23 and exert a pressure outwardly tending to move the pistons 23 of each pair away from each other.

Limiting the movement of the plungers o1' pistons 23 which are adjacent the threaded portions Zta is a contact plate 25 which is provided with hollows or depressions 25d. These depressions 25a are in position to receive and of a shape to nit the rounded ends 23a of the pistons 23. The contact plate 25 surrounds the threaded portions Zta and is held in position by the nut 26 which is threaded on the threaded portion 20a.. By turning the nut 23 on its threaded portion 2da, it is obvious that the compression spring 24 may be made to give a varying pressure on the pistons 23. It is to be here noted that since the main body member 2i is keyed to the shaft 2i] and since the pistons 23 and the contact member 25 and its nut 26 are all directly or indirectly carried by the shaft 26, there will be no tendency of the contact member 25 to turn relatively to the pistons 23 during operation.

Mounted on the shaft 2@ and to turn relatively thereto is the complementary member 27 of the overload clutch. This complementary member 2l has depressions 21a similar to the depressions 25a in the contact members 25, except that these depressions are of a greater diameter than the coa'cting rounded ends 23a of the pistons 23 which coact therewith. The purpose of this construction with the difference in diameters will be later made clear.

Between the bore of the complementary member 21 and the shaft 2li are inner and outer bearing members 28 and 29.

The shaft 2e is provided with a smaller diameter section 2th, upon which is mounted a thrust bearing 30 which contacts the shoulder 20c of the shaft 2t and also the shoulder 2lb of the complementary member 2l. At the end of the shaft 2Q beyond the smaller section 2Gb is 3 a threaded end 26d on which is threaded a nut 3|.

Extending from the complementary -member 21 in the form of the invention illustrated, are a pair of arms 21e which form one part of the universal jointl 32. A pair of arms 33a also connect the universal joint 32 to the driven shaft 33 which serves as a power take-off in the illustrated construction.

The operation of this form of the invention will now be described.

The power is delivered from thedrive or power shaft 23 through key 22, the main body member 2|, the clutch plungers or pistons 23 and the depressions 21a'I of the complementary member 21 to the universal joint 32 and to the driven shaft v33. It is here to be observed that during this transmission of power, there is a complete balance of thrust between the power shaft 23 and the driven shaft 33. This is caused by the thrust of the thrust bearing against the complementary member 21 which in turn presses against the rounded portions 23a, the springs 2d and the contact plate or member 25. It is to be further noted that the main body 2| of the clutch member functions merely asa guide for the plungers or pistons 23, since the axial thrust is all carried by the pistons 23, the key 22 merely preventing relative turning between the shaft 23 and the main body member 2|. The shoulder formed by the limiting collar 2gb keeps the main body member 2| from slipping from its pla-ce on the shaft 2e, If desired, a set screw similar to the part mild of Fig. 4 may be used.

Whenever the torque on the driving shaft 23 as transmitted to thecomplementary member 21 through the ends of the plungers or pistons 23 becomes too great relative to the resistance to turning by the driven shaft33, then there will be a tendency for the pistons 23 to ride up the sides of the depressions 21a. The fact that the depressions 21a have a slightly greater diameter than the rounded ends 23a of the piston-s 23, may in the case of a slight increase above the normal transmitting maximum, cause a slight compression of the springs 24 without the necessity of the releasing action of the clutch to take place. However, a further resistance to the turning of the driven shaftV 33, may be sufficient to cause the springs 22 to be compressed to a suflicient ydistance to cause the rounded ends 23a of the pistons 23 to ride over the edges of the depressions 21a, ,and the clutch will release permitting the power shaft to continue to turn while the driven shaft 33 will be permitted to be retarded or even to stop entirely.

As soon as the obstruction which caused the resistance to the turning of the driven shaft 33 is removed sufficiently, the pistons 23 will again enter the depressions 21a and normal conditions of power transmission will be restored. To

provide for proper lubrication, a lubrication plug Zlc is provided for each boring or cylinder 2|b. In order that when lubricant is forced into the borings or cylinders 2lb it will be facilitated in its travel to the seat of the rounded ends 23a in their depressions 21a and to permit foreign substances to escape, an opening 21d is provided. The adjacent faces of the main body member 2| and the complementary member 21 are close enough together to permit bare. clearance and Amay normally be lled with the lubricant from the cylinders or borings 2 Ib.

In the modified form illustrated in Figs. 4,*5, and 6, there is illustrated a construction wherein `the power may be taken off at right angles to the way |230 is a Woodruff key |22.

4 drive or power shaft by a chain or belt and wherein the overload clutch is supported by a wall. This construction will now be described.

The shaft |22 is provided at its outer end with a threaded portion I'Za and at the inner end of the clutch with a shoulder |202), the purposes of which will be presently made clear. In a key- Mounted on the shaft |20 is the main body |24 of the overload clutch. This main body portion |2| is provided with a keyway |2|a to receive the upper edge of the -woodruff key 522 to hold the main body portion l2! non-rotatively on the shaft |20.

The main body portion |2| is provided with borings or cylinders i2|bthree in number in ,the form of the invention illustrated in Figs. 4, 5, and 6. These cylinders I2 lb are provided each with a pair of complementary plungers or pistons |23. These plungers are hollow and have rounded ends |2311 for a purpose to be made clear. A spring |26 isprovided and has a slightly less outer diameter than the insides of the plungers |23 so `that the springs can be readily inserted in the ends of the plungers |23 as illustrated in Fig. 4.

. Surrounding the shaft H23 is a contact plate or member |25 which is adjustable to vary the compression in the springs |23. The plate or `Contact member |25 is provided with depressions |2511 in which the rounded ends |23a, rest. A pair of lock nuts |23, |260@ are provided on the threaded end |23@ tok hold the contact plate or member |25 in adjusted position.

Adjacent the fianged end I2|c and mounted to rotate relative to the shaft |20, is the complementary member to the main body member |20. This complementary member I have designated |21. Between the complementary member |21 and the shaft |23 are suitable bearing members |28, |29. The complementary member |21 and the shaft |26 are free for relative movement except for the construction which will now be described.

In theY flange |2111 of the complementary member |21 are three equally spaced depressions |21b placed so as to register with the rounded ends |23a of the plungers or pistons E23. It is to be here noted that the diameters of the depressions B21b are slightly greater than the diameters of the rounded ends l23a. The purpose of this relative size will later be made clear. Openings 2id with suitable plugs therefor, are provided so that lubricants may be forced into the cylinders or .borings |2|b to provide lubrication for the plungers or pistons |23. Openings |21c are provided in the deep portions of the depressions V|21@ to assist the lubricant in the borings or ing |3|. The shaft 23 passes through the bearing housing I3! and is journaled on the roller bearing members |32. The housing |3I is provided with a grease groove i3 a.

To close the opening atthe end of the space occupied by the bearing members |32, there is provided a grease washer |33 which has a grease groove |33a to provide the grease groove I3Ia, proper lubrication for the roller bearing members |32.

At the end of the opening through which the roller bearing members |32 are inserted and extending over the end of the grease washer |33 and the bearing housing |3| is a plate washer |34. A second thrust bearing |35 occupies the space between the plate washer |34 and the shoulder |20b of the shaft |20.

In order to take the power from the complementary member |2'| there is provided a driven gear or pulley |36 which is secured to the complementary member |2'| by the studs |3'|. Cut away portions |36a are provided in positions to registerV with the openings |210 to permit escape of foreign substances or excess lubricant.

In order to support the unit as a whole, the housing |3| is provided with a flange |3 Ic'which is secured to the support |38 by the bolts |39. The support 38 is here illustrated as a plate but any suitable support which is sufciently rigid and through which the shaft |20 Iand its coacting parts may pass, may be used.

The operation of the form of the invention illustrated in Figs. 4, 5, and 6 lwill now be described.

Assuming the power to be applied to the shaft |20 and the latter rotating, the key |22 turns the main body member |2| of the clutch. As the plungers or pistons |23 are carried by the main body member |2|, and the plungers or pistons 23 are seated in the depressions |2`|b of the complementary member |21 by the pressure of the springs |24 it follows that the turning of the shaft |20 will also in turn rotate the complementary member |21.

It is to be here noted that the parts are all in equilibrium when the power is being transmitted. The main body member |2| is held in place by the key |22 and the heavy set screws |2Id with no tendency to move endwise. The plungers or pistons |23 are balanced each by the opposite one of its pair. One plunger or piston of a pair pushes on the plate |25 which plate |25 is adjustably held from axial movement rela-tive to the shaft by the nuts |26 and |26a. The other piston or plunger |23 of a pair contacts the depression |2|b of the complementary member |2'| to cause the latter to turn. 'I'he thrust is taken up by the thrust bearing |30 which thrust is in turn transmitted tov the thrust bearing |35. The gap between the flanges |2'|a and I2|c is controlled by the thickness of the plate washer |34. Thus, all thrusts are taken up, in the clutch itself with no thrusts being transmitted to the support member |38.

Whenthe difference between the torque tending to turn the shaft |20 and the main body member |2| and the resistance of the pulley or gear |36 to turning, becomes great enough to force the plungers |23 against the springs |24, thus forcing the plungers or pistons |23 from their respective depressions |2111, the clutch will release by permitting relative rotation between the main body member |2| and the complementary member |21. In case the tendency to unseat the plungers or pistons |23 is very temporary and not sufficient to cause the plungers or pistons |23 to ride entirely out of their "respective depressions |211), the dierence between the diameters of the plungers |23 and the 'depressions |2'|b will permit the plungtom ofthe depressions |2112. After the slight increase in the difference on the forces has ceased, the plungers or pistons will return to the bottoms of the respective depressions.

It is to be understood that the positions of the nuts 26, |26, |26a predetermine the overload and consequently the power conditions under which the respective plungers 23, |23 will release.

It is to be noted that the constructions of the illustrated forms of the invention are such that the driving power members are adapted to become the driven power members and the driven power members are Iadapted to become the driving power members.

While modifications of the invention have been illustrated and described in detail, it is to be understood that the disclosure is merely illustrative and that modications, alterations, and changes may be made without departing from the spirit of the invention and within its scope as claimed.

Having described the invention, what is claimed is:

An overload clutch comprising a rotary driving power member, a rotary driven power member coaxial with the rotary driving power member, a main clutch member mounted on one of the rotary power members and keyed thereto for rotary non-axial movement therewith, a complementary clutch member mounted on the same rotary power member for rotary non-axial movement therewith, the clutch members being coaxial and having faces in close proximity to each other, a series of circumferentially and equally spaced elongated cylindrical openings in the main clutch member with axes parallel to the axis of the main clutch member, a pair of opposed cylindrical plungers in each cylindrical opening, a spring between the plungers of each pair tending to force the plungers away from each other, the plungers having rounded l Yin its face which is adjacent to the main clutch member, and in positions to receive the rounded ends of adjacent plunger members, these openings in the complementary clutch member being of the general shape of the plunger ends but of substantially greater width than the ends of the plunger members.

HARRY C. I-IOLIINGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,141,461 Hazelton June 1, 1915 1,672,964 Stull June 12, 1928 2,157,574 Siesel May 9, 1939 2,164,870 De Salardi July 4, 1939 2,291,407 Paul July 28, 1942 2,292,759 Johnson Aug. 11, 1942 2,333,553 Potgieter et al. Nov. 2, 1943 2,390,908 Young Dec. 11, 1945 

